Underground and partly submerged pipe winding apparatus and method

ABSTRACT

An apparatus and method for lining an underground conduit is disclosed. The apparatus  10  comprises: an annular frame  40  having a crown portion  42  and a base portion  49 ; a strip guide disposed around and supported by the annular frame  40 , the guide arranged to guide a strip  12  around a helical path; a pair of strip pinch rollers mounted to the frame  40  at a position circumferentially about halfway between the crown portion  42  and the base portion  49 ; a drive assembly mounted to the frame for driving the strip  12  downwards into the helical path in a winding direction so as to present an incoming first edge to an adjacent second edge of a wound convolution of the strip; a liquid remover mounted to the frame, the liquid remover arranged to prevent liquid that has adhered to and ascended with the second edge from descending down towards the incoming first edge; and an extruder  80  mounted to the frame  40  for extruding a molten bead of plastic onto the strip  12  at a position just before said overlap.

FIELD OF THE INVENTION

The present invention relates to relining of underground conduits suchas storm water and sewerage pipes. In particular, the present inventionrelates to relining where the pipe is in service and is carrying aliquid.

BACKGROUND

Many techniques are currently used for relining underground conduits.One method of relining conduits involves the digging of a “launchtrench” into which lengths of new pipe are lowered. The pipe lengths arethen slid into the host pipe and are joined together to form acontinuous new pipe. Generally with this method, the conduit beingrelined must be dry. This is often achieved by “over pumping” (pumpingthe water, sewerage or other fluid above the surface so that it bypassessections of the conduit being relined).

Methods that require “over pumping” are undesirable due to the cost andcomplexities involved with the over pumping process.

Another method of relining underground conduits involves placing a pipewinding machine into an access pit and then feeding an elongate plasticstrip into the pit. The machine then winds the strip into an elongatehelical pipe. The applicant has developed various machines and methodsfor winding such a helical pipe. Some of these methods do not require“over pumping” and can be carried out while a conduit being relined isin service. However, these methods are not suitable for producing awelded pipe.

In some applications, it is desirable to provide a fully welded pipe.Fully welded, or continuously welded pipes, are watertight.

It is an object of the present invention to provide a method suitablefor relining an operational underground pipe that eliminates or at leastminimises the need for trenching and provides a continuously weldedpipe.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a methodof lining an underground conduit while the conduit is in servicecarrying a liquid, the method comprising the steps of:

-   -   positioning a pipe winding apparatus within an access pit        adjoining the conduit to be relined, the pipe winding apparatus        having an annular cage through which the liquid flows;    -   feeding the pipe winding apparatus an elongate plastic or        plastic composite strip down into the pit, the strip having        parallel spaced apart first and second edges;    -   driving the strip downwards into the annular cage so as to        present an incoming first edge to an adjacent second edge of a        wound convolution of the strip;    -   preventing liquid that has adhered to and ascended with the        second edge from descending down towards the incoming first        edge;    -   applying a molten bead of plastic to at least one of the        incoming first edge and the adjacent second edge of the newly        wound pipe; and    -   compressing the bead between the incoming first edge and the        adjacent second edge,    -   thereby forming an elongate continuously welded pipe in situ.

Preferably the method further comprises a step of:

-   -   heating at least one of the incoming first edge and the adjacent        second edge of the newly wound pipe,    -   whereby the heating step improves adhesion of the bead to at        least one of the incoming first and adjacent second edges.

Preferably the heating step comprises:

-   -   directing hot gas towards the incoming first edge, the gas        heating the first edge; and    -   directing hot gas towards the adjacent second edge, the gas        heating the second edge.

Preferably the preventing step comprises directing gas towards thesecond edge at a circumferential position on the second edge, thecircumferential position being on an arc between the liquid beingcarried by the conduit and a point at or near the zenith of the secondedge.

Preferably the gas directed towards the second edge is directed in adirection substantially opposite of the direction of travel of thesecond edge.

Alternatively the preventing step comprises wiping the second edge at acircumferential position on the second edge, the circumferentialposition being on an arc between the liquid being carried by the conduitand a point at or near the zenith of the second edge.

Preferably the wiping comprises brushing with a counter rotating brush.

In a further alternative the preventing step comprises inducing apartial vacuum at a circumferential position on the second edge, thecircumferential position being on an arc between the liquid beingcarried by the conduit and a point at or near the zenith of the secondedge.

According to a second aspect of the invention there is provided a methodof lining an underground conduit while the conduit is in servicecarrying a liquid, the method comprising the steps of:

-   -   positioning a pipe winding apparatus within an access pit        adjoining the conduit to be relined, the pipe winding apparatus        having an annular cage through which the liquid flows;    -   feeding the pipe winding apparatus an elongate plastic or        plastic composite strip down into the pit, the strip having        parallel spaced apart first and second edges;    -   winding the strip into the annular cage so as to form adjacent        convolutions;    -   directing a jet of hot gas towards an area spanning adjacent        convolutions of the strip thereby creating a void within the        liquid; and    -   welding adjacent convolutions of the strip together within the        gas void,    -   thereby forming an elongate continuously welded pipe in situ.

According to a third aspect of the invention there is provided anapparatus for lining an underground conduit, the apparatus comprising:

-   -   an annular frame in use having a crown portion and a base        portion;    -   a strip guide disposed around and supported by the annular        frame, the guide arranged to guide a strip around a helical path        when the machine is in use, the path having a zenith;    -   a drive assembly mounted to the frame for driving the strip        downwards into the helical path in a winding direction so as to        present an incoming first edge to an adjacent second edge of a        wound convolution of the strip;    -   a liquid remover mounted to the frame, the liquid remover        arranged to prevent liquid that has adhered to and ascended with        the second edge from descending down towards the incoming first        edge; and    -   an extruder mounted to the frame, the extruder having a nozzle        in use extruding a molten bead of plastic onto the strip at a        position just before said overlap.

Preferably the apparatus further comprises:

-   -   a pair of strip pinch rollers mounted to the frame at a position        circumferentially about halfway between the crown portion and        the base portion, the pinch rollers driven by the drive        assembly.

Preferably the apparatus further comprises:

-   -   a heater mounted to the frame and positioned to heat at least        one of the incoming first edge and the second edge.

Preferably the heater comprises:

-   -   a first gas nozzle mounted to the frame, the first nozzle        arranged to direct hot gas towards the incoming first edge; and    -   a second gas nozzle mounted to the frame, the second nozzle        arranged to direct hot gas towards the second edge.

Alternatively the heater comprises:

-   -   a first radiator mounted to the frame, the first radiator        arranged to radiate heat towards the incoming first edge; and    -   a second radiator mounted to the frame, the second radiator        arranged to direct radiant heat towards the second edge.

Preferably the liquid remover comprises a third gas nozzle mounted tothe frame, the third nozzle arranged to direct gas towards the secondedge at a circumferential position on the second edge, thecircumferential position being on an arc between the liquid beingcarried by the conduit and a point at or near the zenith of the secondedge,

-   -   wherein in use the third nozzle prevents liquid that has adhered        to and ascended with the second edge from descending down        towards the incoming first edge.

Alternatively the liquid remover comprises a wiper mounted to the frame,the wiper engaging the second edge at a circumferential position on thesecond edge, the circumferential position being on an arc between theliquid being carried by the conduit and a point at or near the zenith ofthe second edge,

-   -   wherein in use the wiper prevents liquid that has adhered to and        ascended with the second edge from descending down towards the        incoming first edge.

Preferably the wiper comprises a rotating brush.

In a further alternative the liquid remover comprises a partial vacuuminducing assembly mounted at a circumferential position on the secondedge, the circumferential position being on an arc between the liquidbeing carried by the conduit and a point at or near the zenith of thesecond edge.

Preferably the annular cage is substantially cylindrical in shape.

Preferably the crown portion comprises a lifting member liftable by acrane. According to a fourth aspect of the invention there is providedan apparatus for lining an underground conduit while the conduit is inservice carrying a liquid, the apparatus comprising:

-   -   a cylindrical frame in use having a crown portion and a base        portion;    -   a plurality of substantially parallel spaced apart rollers        disposed around and supported by the cylindrical frame, the        rollers forming a guide to guide a strip around a helical path        when the machine is in use, the path having a zenith;    -   a pair of strip pinch rollers mounted to the frame at a position        circumferentially about halfway between the crown portion and        the base portion;    -   a primary drive assembly mounted to the frame and operably        connected to the pinch rollers for driving the strip downwards        into the helical path in a winding direction so as to present an        incoming first edge to an adjacent second edge of a wound        convolution of the strip;    -   a liquid remover mounted to the frame, the liquid remover        arranged to prevent liquid that has adhered to and ascended with        the second edge from descending down towards the incoming first        edge; and    -   an extruder mounted to the frame, the extruder having a nozzle        in use extruding a molten bead of plastic onto the strip at a        position just before said overlap.

Preferably the apparatus further comprises a secondary drive assemblymounted to the frame, the secondary drive assembly providing additionaldriving torque to the primary drive assembly,

-   -   wherein the additional driving torque allows the pipe to be        produced in longer lengths in situ.

Specific embodiments of the invention will now be described in somefurther detail with reference to and as illustrated in the accompanyingFigures. These embodiments are illustrative, and are not meant to berestrictive of the scope of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

A preferred embodiment of the invention is illustrated in theaccompanying representations in which:

FIG. 1 shows a schematic cross sectional view of an underground conduitbeing relined using a method according to the invention.

FIG. 2 a is a perspective view of a pipe winding apparatus used with themethod of FIG. 1.

FIG. 2 b is a detailed perspective view of the top of the apparatus showin FIG. 2 a.

FIG. 3 a is a schematic cross sectional view showing the method andapparatus illustrated in FIGS. 1, 2 a and 2 b in more detail.

FIGS. 3 b, 3 c and 3 d are similar views to that of FIG. 3 a, but showalternative embodiments.

FIG. 4 a is a perspective detailed view of the apparatus shown in FIGS.2 a and 2 b.

FIG. 4 b is a perspective detailed view of the apparatus shown in FIGS.2 a and 2 b but with an alternative heater means.

FIG. 5 shows a cross sectional view of a plastic composite strip(profile) used in the method illustrated in FIGS. 1 and 3 a; and

FIG. 6 is a perspective view of a pipe produced by the methodillustrated in the preceding Figures.

Referring to FIG. 1, a pipe winding apparatus 10 is shown in positionwithin an access pit 3 adjoining a conduit 5 to be relined. The pipewinding apparatus 10 has an annular frame 40 (best shown in FIG. 2 a)through which liquid can flow. Thus, the conduit or pipe 5 can berehabilitated while in service (carrying storm water or sewage forinstance).

A spool 160 positioned above ground feeds the pipe winding apparatus 10with an elongate plastic or plastic composite strip 12 down into the pit3. Various strips or profiles can be used. FIG. 5 shows a crosssectional view of two adjacent convolutions of a composite strip that issuitable for use with the method of the invention.

Referring to FIGS. 2 a, 3 a and 4, the apparatus 10 includes an annularcylindrical frame 40 that in use has a crown portion 42 that is liftableby a crane having a hook 2. The annular frame also has a base portion 49that in use may rest on the conduit 4. The apparatus 10 also includes aplurality of substantially parallel spaced apart rollers 41 disposedaround and supported by the annular frame 40. The rollers 41 form aguide to guide the strip 12 around a helical path when the machine is inuse. The path has a zenith adjacent the crown of the annular frame 40.

The apparatus 10 further includes a pair of primary strip pinch rollers71 and 72 mounted to the frame 40 at a position circumferentially abouthalf way between the crown portion 42 and the base portion 49. A driveassembly 53 is also mounted to the frame 40 for driving the strip 12into the helical path in a winding direction such that the adjacent edgeportions 16 and 18 of adjacent convolutions of the strip 12 overlap.

A gas nozzle 99 is mounted to the frame 40 and is arranged to direct gas(in this embodiment, air) in a direction across and having componentstowards the zenith of the strip path and against the winding directionof the strip 12.

The gas nozzle 99 prevents the water and debris (accretions) 9illustrated in FIG. 3 a from travelling down towards the welding area asis clearly illustrated in the schematic of FIG. 3 a.

FIG. 2 b shows an additional nozzle 99′. This nozzle helps ensure thatthe edge of the strip is cleared of water and debris. In otherembodiments of the invention, the additional nozzle will not be needed.Both nozzles are fed by compressed air through a supply line 108 and amanifold 105.

Various other means can be employed to prevent accretions travellingdown towards the welding area. Some of these alternative means are shownin FIGS. 3 b, 3 c and 3 d.

Referring to FIGS. 3 b and 3 c, liquid removers in the form of wipersare shown. The wiper of FIG. 3 b is a counter-rotating brush 199 drivenin a direction 197 by a motor 198. While various motors can be employed,preferably the motor 198 is either pneumatically or hydraulicallydriven. An alternative simplified wiper is shown if FIG. 3 c. This wiper199′ is in the form of a flexible rubber or plastic member.

A further alternative liquid remover is shown in FIG. 3 d. The liquidremover of FIG. 3 d comprises a partial vacuum inducing assembly 196.This assembly includes a suction nozzle 99.

In FIG. 2 b, an alternative lifting eye 112 is shown to the liftingframe 111 shown in FIG. 2 a.

The winding apparatus shown in FIGS. 2 a, 2 b and 5 is driven by ahydraulic motor 60 (not shown). The hydraulic motor 60 is able tooperate in harsh conditions and provides a high torque output to drivethe strip 12 around the inside of the rollers 41. An optional secondarydrive assembly having pinch rollers 121 and 122 as shown in FIG. 3 d maybe provided. The secondary drive assembly provides additional drivingtorque which can allow parts to be produced in longer lengths in situ.FIG. 3 d shows the primary drive assembly 70 and the secondary driveassembly 120. The secondary drive unit can of course be employed inother embodiments of the invention schematically illustrated in FIGS. 3a, 3 b and 3 c.

Referring to FIG. 2 a, an extruder 80 forms part of the apparatus 10.The extruder 80 is fed with plastic pellets through a supply tube 81.The extruder 80 has a nozzle 85 that applies a molten bead of plastic tothe incoming first edge 16 as is most clearly shown in FIG. 4 a.

Polyethylene plastic can be used for both the strip 12 and as the feedstock for the extruder 80. Polyethylene is a low cost plastic that hasexcellent chemical properties making it highly suitable forrehabilitating pipes. While it lacks the stiffness of PVC, when combinedwith a reinforcing strip such as the strip 30 illustrated in FIG. 5, astiff pipe can be wound. While the method of the invention isparticularly suitable for polyethylene pipes, other plastics may beused.

After the molten bead of plastic has been applied to the incoming firstedge 16, the bead is compressed between the incoming first edge 16 andthe adjacent second edge 18 between a pinch roll assembly of primarydrive assembly 70 having opposed rollers 71 and 72. FIG. 5 shows theresultant welded seam 19. As this is a continuous process, a continuousweld is created.

While in the drawings the bead is shown being applied to the incomingfirst edge 16, in other embodiments of the invention, the bead may beapplied to the adjacent second edge.

Referring to FIGS. 2 b and 3 a, it can be seen that conduit 94 carrieshot air towards nozzles 95 and 97. Nozzle 97 directs hot air towards theadjacent second edge in a direction substantially opposite the directionof travel of the adjacent second edge. The hot air exiting nozzles 95and 97 preheats and dries the edges of the strip 12 to facilitate thewelding process. Alternative means of pre-heating the edges of the stripto facilitate the welding process can be used. For instance, radiantheaters such as the electric resistance radiant heaters 61 and 62 shownin FIG. 4 b may be used. Other heating means such as friction means mayalso be used to facilitate the welding process.

The apparatus described and illustrated in FIG. 4 can be used to line anunderground conduit while the conduit is in service carrying a liquid.Once the pipe winding apparatus has been positioned within an access pitadjoining the conduit to be relined, it is fed with an elongate plasticor plastic composite strip 12 down through an access pit 3 as isillustrated most clearly in FIG. 1. The strip 12 is driven downwardsinto the cylindrical cage 40′ so as to present an incoming first edge 16to an adjacent second edge 18 of a wound convolution of the strip 12.The high velocity air directed from nozzles 99 and 99′ prevents liquidand/or other accretions that have adhered to it ascending with thesecond edge 18 and from descending down towards the incoming first edge16. Hot air is directed to both the incoming first edge 16 and theadjacent second edge 18 in order to heat the edges before a moltenbeaded plastic is applied to either one of the incoming first edge 16 oradjacent second edge 18 and before compressing the bead between theincoming first edge 16 and the adjacent second edge 18.

With the method described thus far, a pipe can be wound in situ whilethe conduit 4 is still in service. If however, the conduit 4 is runningat or near capacity then the water level illustrated in FIG. 3 a will besomewhat higher. According to a further aspect of the invention a methodis provided that will operate in such conditions. A method embodying thesecond aspect of the invention includes a step of directing a jet of hotgas towards an area spanning adjacent convolutions of the strip therebycreating a void within the liquid. Welding of adjacent convolutions ofthe strip together then occurs within the gas void. In other respects,such a method embodying this aspect of the invention is similar to thefirst embodiment described above.

The actual pipe 100 wound by either of the above-described methods isillustrated in the perspective view of FIG. 6. This pipe is acontinuously welded pipe that provides a watertight conduit of highintegrity.

While the present invention has been described in terms of preferredembodiments, in order to facilitate a better understanding of theinvention, it should be appreciated that various modifications can bemade without departing from the principles of the invention. Therefore,the invention should be understood to include all such modificationswithin its scope.

The claims defining the invention are as follows:
 1. A method of liningan underground conduit while the conduit is in service carrying aliquid, the method comprising the steps of: positioning a pipe windingapparatus within an access pit adjoining the conduit to be relined, thepipe winding apparatus having an annular cage through which the liquidflows; feeding the pipe winding apparatus an elongate plastic or plasticcomposite strip down into the pit, the strip having parallel spacedapart first and second edges; driving the strip downwards into theannular cage so as to present an incoming first edge to an adjacentsecond edge of a wound convolution of the strip; preventing liquid thathas adhered to and ascended with the second edge from descending downtowards the incoming first edge; applying a molten bead of plastic to atleast one of the incoming first edge and the adjacent second edge of thenewly wound pipe; and compressing the bead between the incoming firstedge and the adjacent second edge, thereby forming an elongatecontinuously welded pipe in situ.
 2. A method as claimed in claim 1further comprising a step of: heating at least one of the incoming firstedge and the adjacent second edge of the newly wound pipe, whereby theheating step improves adhesion of the bead to at least one of theincoming first and adjacent second edges.
 3. A method as claimed inclaim 2 wherein the heating step comprises: directing hot gas towardsthe incoming first edge, the gas heating the first edge; and directinghot gas towards the adjacent second edge, the gas heating the secondedge.
 4. A method as claimed in claim 1 wherein the preventing stepcomprises directing gas towards the second edge at a circumferentialposition on the second edge, the circumferential position being on anarc between the liquid being carried by the conduit and a point at ornear the zenith of the second edge.
 5. A method as claimed in claim 4wherein the gas directed towards the second edge is directed in adirection substantially opposite of the direction of travel of thesecond edge.
 6. A method as claimed in claim 1 wherein the preventingstep comprises wiping the second edge at a circumferential position onthe second edge, the circumferential position being on an arc betweenthe liquid being carried by the conduit and a point at or near thezenith of the second edge.
 7. A method as claimed in claim 6 wherein thewiping comprises brushing with a counter rotating brush.
 8. A method asclaimed in claim 1 wherein the preventing step comprises inducing apartial vacuum at a circumferential position on the second edge, thecircumferential position being on an arc between the liquid beingcarried by the conduit and a point at or near the zenith of the secondedge.
 9. A method of lining an underground conduit while the conduit isin service carrying a liquid, the method comprising the steps of:positioning a pipe winding apparatus within an access pit adjoining theconduit to be relined, the pipe winding apparatus having an annular cagethrough which the liquid flows; feeding the pipe winding apparatus anelongate plastic or plastic composite strip down into the pit, the striphaving parallel spaced apart first and second edges; winding the stripinto the annular cage so as to form adjacent convolutions; directing ajet of hot gas towards an area spanning adjacent convolutions of thestrip thereby creating a void within the liquid; and welding adjacentconvolutions of the strip together within the gas void, thereby formingan elongate continuously welded pipe in situ,
 10. An apparatus forlining an underground conduit, the apparatus comprising: an annularframe in use having a crown portion and a base portion; a strip guidedisposed around and supported by the annular frame, the guide arrangedto guide a strip around a helical path when the machine is in use, thepath having a zenith; a drive assembly mounted to the frame for drivingthe strip downwards into the helical path in a winding direction so asto present an incoming first edge to an adjacent second edge of a woundconvolution of the strip; a liquid remover mounted to the frame, theliquid remover arranged to prevent liquid that has adhered to andascended with the second edge from descending down towards the incomingfirst edge; and an extruder mounted to the frame, the extruder having anozzle in use extruding a molten bead of plastic onto the strip at aposition just before said overlap.
 11. An apparatus as claimed in claim10 further comprising: a pair of strip pinch rollers mounted to theframe at a position circumferentially about halfway between the crownportion and the base portion, the pinch rollers driven by the driveassembly.
 12. An apparatus as claimed in claim 10 further comprising: aheater mounted to the frame and positioned to heat at least one of theincoming first edge and the second edge.
 13. An apparatus as claimed inclaim 11 wherein the heater comprises: a first gas nozzle mounted to theframe, the first nozzle arranged to direct hot gas towards the incomingfirst edge; and a second gas nozzle mounted to the frame, the secondnozzle arranged to direct hot gas towards the second edge.
 14. Anapparatus as claimed in claim 12 wherein the heater comprises: a firstradiator mounted to the frame, the first radiator arranged to radiateheat towards the incoming first edge; and a second radiator mounted tothe frame, the second radiator arranged to direct radiant heat towardsthe second edge.
 15. An apparatus as claimed in claim 10 wherein theliquid remover comprises a third gas nozzle mounted to the frame, thethird nozzle arranged to direct gas towards the second edge at acircumferential position on the second edge, the circumferentialposition being on an arc between the liquid being carried by the conduitand a point at or near the zenith of the second edge, wherein in use thethird nozzle prevents liquid that has adhered to and ascended with thesecond edge from descending down towards the incoming first edge.
 16. Anapparatus as claimed in claim 10 wherein the liquid remover comprises awiper mounted to the frame, the wiper engaging the second edge at acircumferential position on the second edge, the circumferentialposition being on an arc between the liquid being carried by the conduitand a point at or near the zenith of the second edge, wherein in use thewiper prevents liquid that has adhered to and ascended with the secondedge from descending down towards the incoming first edge.
 17. Anapparatus as claimed in claim 16 wherein the wiper comprises a rotatingbrush.
 18. An apparatus as claimed in claim 10 wherein the liquidremover comprises a partial vacuum inducing assembly mounted at acircumferential position on the second edge, the circumferentialposition being on an arc between the liquid being carried by the conduitand a point at or near the zenith of the second edge.
 19. An apparatusas claimed in claim 10 wherein the annular cage is substantiallycylindrical in shape.
 20. An apparatus as claimed in claim 10 whereinthe crown portion comprises a lifting member liftable by a crane.
 21. Anapparatus for lining an underground conduit while the conduit is inservice carrying a liquid, the apparatus comprising: a cylindrical framein use having a crown portion and a base portion; a plurality ofsubstantially parallel spaced apart rollers disposed around andsupported by the cylindrical frame, the rollers forming a guide to guidea strip around a helical path when the machine is in use, the pathhaving a zenith; a pair of strip pinch rollers mounted to the frame at aposition circumferentially about halfway between the crown portion andthe base portion; a primary drive assembly mounted to the frame andoperably connected to the pinch rollers for driving the strip downwardsinto the helical path in a winding direction so as to present anincoming first edge to an adjacent second edge of a wound convolution ofthe strip; a liquid remover mounted to the frame, the liquid removerarranged to prevent liquid that has adhered to and ascended with thesecond edge from descending down towards the incoming first edge; and anextruder mounted to the frame, the extruder having a nozzle in useextruding a molten bead of plastic onto the strip at a position justbefore said overlap.
 22. An apparatus as claimed in claim 21 furthercomprising a secondary drive assembly mounted to the frame, thesecondary drive assembly providing additional driving torque to theprimary drive assembly, wherein the additional driving torque allows thepipe to be produced in longer lengths in situ.